<div dir="ltr">Hi Wallace,<div><br></div><div>What you have here is not a charting problem, but a signal processing problem.</div><div><br></div><div>I've not done a lot of work in the signal processing field, but I would suggest you do some research into Kalman filters - these may be what you are looking for.</div><div><br></div><div>I would feed the raw data through a filter, and then feed the filtered data to the charting component.</div><div><br></div><div>Another (possibly simpler) filtering approach would be to apply a low-pass filter to the data.</div><div><br></div><div>As usual, Google is your friend with these things :-) (try search for discrete time low pass filter)</div><div><br></div><div>Cheers,</div><div>Alistair.</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, 11 May 2021 at 18:25, Marshland Engineering <<a href="mailto:marshland@marshland.co.nz">marshland@marshland.co.nz</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">After much searching, I cannot find 3rd part components to use. Am I search<br>
for the wrong thing ? <br>
<br>
This is version 2 of my dyno. The old version was a bought package that used a<br>
Freq to voltage converter and then an A to D converter for the input to the PC<br>
but he resolution was very poor and I had to do a lot of fiddling with higher<br>
power bikes to get reasonable data. <br>
<br>
My idea with this version is to get as high a resolution as I can.<br>
<br>
If you have some time to spare, here is my logic.<br>
<br>
The drum speed goes from 45 to 65 kph over 4 seconds. Or 12.5 to 18 m/s <br>
I'm sampling at 30 hz<br>
<br>
Over the time period, I take 120 samples. The average rate of change of each<br>
sample is 0.17 kph. If I take the 0.17m over the average speed range, it is<br>
1/330 or 0.3 %. That is quite optimistic for dyno, but it where I'm starting. <br>
<br>
Each timing period from the drum represents 200mm on the surface and the<br>
ATMEGA can count up to 65535 clock cycles in this period. My resolution on<br>
the ATMEGA is therefore 0.003 mm per clock cycle. <br>
<br>
I think I have enough resolution for what I want. <br>
<br>
One of the problems is that the wheel to drum, engine speed changes etc are<br>
not exactly linear. I believe this is where the noise is from, however, the<br>
data below the noise is valid. <br>
<br>
I can improve the plots by fewer samples, ie getting a bigger rate of change<br>
between samples but then my resolution will decrease. <br>
<br>
Cheers Wallace. <br>
<br>
<br>
<br>
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</blockquote></div>